To Idle or Not Idle

Bill_P

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Best option is to hook up a propane heater and direct the airflow straight to the grill. Be careful not to get too close to the front though, less you melt the paint.

You'll want to wait on starting the engine until the average temp of the engine bay is between 60-80 degrees Fahrenheit.

Once started, wait exactly 10 minutes. Too little and the ECU won't be able to get enough readings to properly adjust to the real ambient air temperature without the propane heater. Too long and there will be too many readings (same issue).

Now, at the ten minute mark turn the engine off. Then Quickly turn off the heater and store safely. Don't take too long as the engine can cool faster than most think. Especially if the Temps are sub 20 degrees Fahrenheit. Take too long to do this and you'll have to restart the procedure all over again.

Once done, next Remote Start the Jeep. If you don't have remote start, then you'll have to start it with the driver door ajar. The goal is to let the Jeep know you don't intend to immediately drive off so it goes into a warm-up procedure.

Remember the ambient temperature of the engine bay before? Yup, the Jeep didn't go into a warm up procedure then because it detected warm air already. BUT NOW it'll detect the cold air...

Here's the bit that Jeep screwed up from factory. We've just forced the Jeep to warm up in a safe controlled manner. The Jeep now does its automated warm up procedure (#ECU Code WMU420) and makes sure proper fluid pressure and rpms are ran to safe operating parameters. IF WE DIDN'T warm the engine up ourselves, then the initial pressures would have been all over the map. This is ok a few times, but for us that live in crazy weather states like FL; having to warm the engine up in cold temperatures every day for months on end will result in blown head gaskets.

With the Jeep started, listen for the RPMs to run normal/settle towards idle as specified in your manual. At this point, she's safe to drive all you want!

Hope this helps! ;)
Is it safe if I redirect some of the propane heat so it warms up the blinker fluid to the proper operating temp?

 

OrneryBear

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As others have said, let the vehicle idle for a little bit to get oil flowing and some temperature in it, and then go. I would add, an important detail is to not "beat on" the vehicle until the engine comes up to normal operating temps. Just drive calm and accelerate slow while keeping rpms down.
 

Tncdrew

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3.6 here. I have always gone off the rpm’s. When first starting the Jeep, the rpm’s will be a touch higher and then settle after a minute or so (never timed it). Once settled off I go. Now in extreme cold I’ll let it warm up until the cabin is comfortable.
This 👆 👍
 

Old Dogger

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It's not that cold in Phoenix, even in the Winter months. But I always wait until the idle RPM drops down. Then I go easy on the throttle for the first mile or so.
 

redsyphon

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Crap!! I’ve been doing it wrong all these years. I use an electric heater! Guess I need to start shopping for a propane one. How badly do you think I’ve hurt my engine?
Oh man... well, you're better off than most with the engine block heater. I'd definitely check the spark plugs though! They're probably not torqued to spec with all the rapid cooling and heating (i.e. expansion of metals)!
 


redsyphon

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Is it safe if I redirect some of the propane heat so it warms up the blinker fluid to the proper operating temp?
Good call! I'll be looking into this myself. My current fluid is probablyshot. Oh well, I needed to change the blinker fluid out anyways at next oil change.
 

Reinen

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The JL is a modern vehicle, not a 70's vehicle. The best thing to do is to just start it and drive it, nice and easy, until the engine is up to temp. Driving like that will heat the engine up faster with less wear than idling to temperature.

Unless it's SO cold that you need to get into engine block and battery heaters, but that is only necessary if the Jeep is routinely parked in temps below 5F. Even then, once the engine fluids are warmed above that level it's still better to just drive it very gingerly until it is fully up to temperature.

It was only your grandfather's car that needed to be warmed up, not yours.
 

6.2Blazer

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Proper process is to start the engine, wait the 30-ish seconds for RPM to "settle," then take off. Engine doesn't matter. The goal is to get the vehicle to operating temperature, which happens significantly faster if you're driving.

Idling your car just to heat it up isn't good for the engine (doing it a few times obviously won't make it explode but it's poor practice in the loooong run), wastes gas, and pollutes the air.
Please provide official documentation that this is the "proper" process for starting an engine, or that it is bad for the engine. I'm not talking about quoting some other random person on the internet, but some official document or statement from a manufacturer.
Sure, you do use some extra gas and thus pollution letting the car idle but it is extremely small compared to actually driving. Idling a car for 10 minutes (common remote start times) consumes around 0.03 to 0.05 gallons of fuel. To put this in perspective a JL will consume more fuel simply pulling out of your driveway and accelerating up to speed on the road..........or pulling through the Starbuck's drive thru on the way to work, and you would use way more fuel running out to McDonald's to get lunch. Of course if you are that concerned about the environment then I'm not sure why somebody would buy a JL to begin with because they are far from the most efficient vehicles on the road...........


^ This! OP just get in watch or even listen to the rpms. After you start the engine they will run above 1500 for 30 seconds or so and then they will drop under 1000. At this point the engine will not get any hotter just sitting there. So you are good to go.
That statement is not correct at all, not even close. The engine will definitely get hotter if you let if sit there and idle, and would expect it to get at, or at least near, full operating temperature. If it's only 30 degrees F outside and you start an engine for only 30 seconds it will hardly warm up at all. The oil and coolant would still be cold and the only thing that may be warm at all are the exhaust manifolds, so overall average of the engine is maybe 50F????? You definitely wouldn't have any heat coming out of the vents (and if you don't know the heat comes from the engine....). If I remote start my car and let it run for the 10 minute time you definitely have heat coming out of the vents and the temp gauge will be up over 150 F. If you keep it running for another 5-10 minutes it will be up around the 200F operating range.
 

stumblinhorse

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I don’t have a 4Xe, but I did have a couple of days while in Manitoba last year over Christmas that temps plummeted below -60F (-52c) overnight. We were at the Farm so no way to keep the Jeep (3.6 e-torque) in the garage. Come morning it started, but then the electrical went haywire, the wipers started going at 1/8th speed across the windshield, all the lights on the dash came on and it died. The battery had frozen. Took it inside and let it thaw out by the furnace for several hours and she was good to go…. But if that had been a 4Xe, I’m not sure that would have been so easy.


I don’t think most folks with opinions in this thread understand what “cold” is.
Similar cold here. If it starts it gets driven…. At -40 Or lower It is a good idea to start it about every 4-6 hours. People don’t know what cold is really. 28*F this morning. My procedure for diesels or gas, get in, start, drive…. But what do I know, my diesel only has 350k miles on it…
 


azjl#3

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Start it drive it, that is what the engineers expect of you.

That said, if you live in truly cold places, well below 32/0, then I would keep it heated in a garage. Next best thing is a heated silicone glue on pad for the oil pan. Plug it in on a timer, and your oil is warm when you come out, do not leave it on all night.
 

dcmdon

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This debate has raged in the General Aviation community for decades. The consensus there is that if the engine has run ‘recently’ there is enough lubrication and oil film over everything in the engine, that starting really doesn’t hurt anything.

Secondly, it is agreed that oil temps must come up (at least 100 dF) in a aviation piston before any medium to high power loads are put on the engine. This ensures adequate ‘live’ lubrication is happening when RPMs are increased.

I’m no expert but I think you’re safe to start and idle your Jeep, and letting things come up to temp before your mash the throttle are good practices.
Its interesting that you mentioned this, I was thinking the same thing.

I was lucky in my plane, I had separate ignition switches from my starter push button (Experimental RV4). I'd crank it with the mixture pulled and the ignitions off and then after a couple of blades I'd push the mixture in and turn on the ignitions.
 

sconrad24

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Please provide official documentation that this is the "proper" process for starting an engine, or that it is bad for the engine. I'm not talking about quoting some other random person on the internet, but some official document or statement from a manufacturer.
Sure, you do use some extra gas and thus pollution letting the car idle but it is extremely small compared to actually driving. Idling a car for 10 minutes (common remote start times) consumes around 0.03 to 0.05 gallons of fuel. To put this in perspective a JL will consume more fuel simply pulling out of your driveway and accelerating up to speed on the road..........or pulling through the Starbuck's drive thru on the way to work, and you would use way more fuel running out to McDonald's to get lunch. Of course if you are that concerned about the environment then I'm not sure why somebody would buy a JL to begin with because they are far from the most efficient vehicles on the road...........



That statement is not correct at all, not even close. The engine will definitely get hotter if you let if sit there and idle, and would expect it to get at, or at least near, full operating temperature. If it's only 30 degrees F outside and you start an engine for only 30 seconds it will hardly warm up at all. The oil and coolant would still be cold and the only thing that may be warm at all are the exhaust manifolds, so overall average of the engine is maybe 50F????? You definitely wouldn't have any heat coming out of the vents (and if you don't know the heat comes from the engine....). If I remote start my car and let it run for the 10 minute time you definitely have heat coming out of the vents and the temp gauge will be up over 150 F. If you keep it running for another 5-10 minutes it will be up around the 200F operating range.
50 degrees is certainly enough to get the oil flowing, oil maintains viscosity down to pretty low temps. I wouldnt floor it at that point but its good enough to start out. The OP the only asked at what point is it ok to start driving. It was not asked after how long would the Jeep be nice and toasty.
 
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Sazabi19

Sazabi19

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I'm pretty fine with it being cold in the cab for the first few mins, these things have some beastly heaters and it will be warm in no time. I also love winter and cold temps, though if I didn't have cold wind with it I'd be OK with that. I'm looking at this from the vehicle's mechanical health really. Sounds like most people think idling to simply warm up is only a waste of time and a creature comfort. Honestly not what I thought the general consensus would be, but that's alright.

I also didn't know if a turbo needed any special care during the cold.
 

jaymz

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Start it and go.

Many will tell you that with a turbo it's more important to idle for a minute or so when you shut it off to keep fresh oil flowing to the turbo while it spools down. I don't know if it's legit advice or not, but it makes theoretical sense.

 

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